VKernel has put together several resources on sizing memory for your virtual machines. White papers include:
- VM Memory (vRAM) Sizing Considerations - gain a deeper understanding of VMware's memory over-commitment capabilities and which VMware system metrics to analyze to make VM memory sizing less painful.
- Memory Management Metrics for VMware Environments - provides information on the key VMware memory metrics you should use for VM (virtual machine) memory allocation sizing and VM performance issue monitoring, as well as recommendations on how to make these assessments when large memory pages are in use.
- VM Memory Sizing and the Impact on VMware Pricing
- Managing VM Memory in VMware - a blog series that discusses tips and tricks for managing VM memory in VMware so that all the virtual machines get the resources they need.
Even though most of these are aimed at VMware, some of the techniques and information applies to other hypervisors as well.